The object of the project is to relate the visually guided behavior of monkeys to cerebral processes. Investigations will be concerned with the following problem areas: (1) Extrageniculostriate vision, i.e. the visual capacities which remain after exclusion of the geniculostriate system including the effective stimulus parameters and the critical structures necessary for these functions. (2) The influence of sensory interactions upon visual perception. (3) The mechanisms of visuo- oculomotor integration and its relationship to detection of movement. (4) The anatomic description of certain portions of the visual and oculomotor pathways. Behavioral methods will include the determination of psychophysical thresholds of visual function, the performance of complex visual habits involving forms and figure-ground articulations, transposition experiments, and the study of an unlearned response such as nystagmus produced either by successive moving stimuli (optokinetic nystagmus) or by intermittent photic stimulation (flicker-induced nystagmus). Nystagmus will be recorded by electro-oculography and analyzed via a small general purpose digital computer. The importance of cortical and subcortical structures in visual behavior will be determined with the ablation technique. Anatomic investigations will be mostly concerned with the synaptic organization of termination sites of retinal and corticofugal fibers as revealed by the Golgi method and electron microscopy.